SU1046918A1 - Pulse generator - Google Patents

Abstract

A PULSE GENERATOR, containing a series-connected alternating current source and a threshold element, a negative-impedance copier, a first you connected a capacitor: to the common bus / water, in order to ensure the POSSIBILITY of controlling the amplitude of the output pulses, diode, a second current source and a transistor connected by a gap between the first current source and the second capacitor output, and the base to the second current source, while the diode is connected to three-way parallel to the gap, the collector of the transistor. 1G / G I I I I 4ii O) CO

Description

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zw./ The invention relates to a pulse technique and is intended for forming pulses. There are known relaxation pulse generators made on the basis of a storage capacitor, parallel to which a threshold element with negative resistance C1 J and 12 is connected. The common drawback of these devices is the instability of the amplitude of the output pulses, which is determined by the instability of the turn-on voltage of the threshold. negative, the most.e. (Closest in technical essence to the proposed is a pulse generator containing a series-connected source a negative negative resistance element and a capacitor connected by one output to a common bus. The disadvantage of such a generator is the impossibility of controlling the amplitude of the output signals, since the capacitor in it is charged before the switching voltage of the threshold element, which is not is regulated and determined only by the internal properties of the threshold element with negative resistance. The purpose of the invention is to provide the possibility of controlling the amplitude of the output pulses. .- The goal is achieved by the fact that a pulse generator containing a series-connected first current source and a threshold element is achieved. negative resistance, a capacitor connected to the common bus by the first output, a voltage limiter, a diode, a second current source and a transistor connected by a collector-emitter gap between the first current source and the second capacitor output, and a diode connected to the base anti-parallel to the collector-emitter gap of the transistor. In FIG. Figure 1 shows the principle of the electrical circuit of the pulse generator; in fig. 2 shows an example of using a multi-phase generator; in fig. 3 - diagrams (a, b, c, d) of the output signals of a multi-phase generator. The pulse generator (Fig. 1) contains a current source 1 ;, obtained, for example, by using a voltage source 2 and a resistor 3, a threshold element 4 with negative resistance, c. Which can be used any active two-pole voltage controlled, for example, a dynistor (a thyristor with a zener diode in the control circuit of the control electrode with the anode), a capacitor 5, a diode 6, a voltage suppressor 7, made for example in the form of a diode 8, connected to the source 9 of the reference voltage, the transistor 10 connected by the base to the second current source 11, made in particular on the resistor 12 connected to the first current source 1. The pulse generator can operate in self-oscillation mode or in standby mode. In the self-oscillation mode, the generator operates in the case that the sum of the currents of the sources 1 and 11 is less than the magnitude of the holding current of the threshold element 4 in the on state. Consideration of work for this case will begin with the moment the threshold element 4 is turned off. From this moment condensation begins to charge. torus 5 with the emitter current of transistor 10 equal to the sum of the base currents (source current 11 / and collector f current source 1). In this case, the voltage limiter 7, shunted by the input circuit of the transistor 10, does not consume current. As the capacitor 5 is charged, the voltage at the emitter increases, and hence at the base of the transistor 10. During the charging of the capacitor 5, the diode 5 6 is locked back by a bias voltage drop in the collector-emitter section of the transistor 10. The voltage acting on the threshold element 4 is equal to the sum of the voltages on the capacitor and on the collector-emitter section of the transistor 10. When the voltage on the capacitor 5 approaches the level limitations of the delimiter 7, the base current of the transistor 10 decreases (by reducing the voltage applied to its base-emitter1 junction} and the resistance of the collector-emitter section of the transistor increases. When the voltage on threshold element 4 is reached, the turn-on threshold value the cathode of the diode 6 is turned on to the common bus, thereby closing the discharge circuit of the capacitor 5. The capacitor 5 is discharged through the diode b and the threshold element 4. The total current from and flows through the threshold element 4 at this stage of operation 1 and the source of current 11 and discharge capacitor 5. As the discharge current of the capacitor 5 via a threshold element 4 at №naets. When the current through the threshold element 4 becomes less than the current holding the element in the on state, it turns off. Further, the processes are repeated. By varying the voltage of the source 9, which sets the level to which the capacitor 5 is charged, it is possible to adjust the amplitude of the output pulses. Frequency control is carried out by changing the magnitude of the current sources and AND, determining the speed, charge of the capacitor 5, as well as changing the limiting level of the limiting bodies 7. Saw-shaped output pulses can be removed from the emitter of the transistor 10. Short-duration output pulses With a high steepness of the front can be removed from the load resistors 13 and 14, connected in series with the capacitor 5 and the threshold element 4, respectively. In the standby mode, the generator operates in the case when the current value of source 1 is greater than the current value of the threshold element 4. To transfer the generator to a temporarily steady state, it is necessary to interrupt the current for a short time through the threshold element 4. To this end, the key transistor can be used 15, a shunt threshold element 4 controlled by pulses from a source of 16 input pulses. In standby mode, the generator works as follows. In the initial state, the threshold element 4 is turned on and shunts the capacitor 5. When the input pulse arrives, the transistor 15 becomes saturated and shunts the threshold element 4, then off-s. At the end of the input pulse, transistor ort 10 is turned on and the charge of the capacitor 5 starts up to the limiter limiter 7 level. After that, the threshold element 4 is activated, then the circuit returns to its initial state. The output pulses, removing e from the resistors 13 and 14, are delayed relative to the trailing edge of the input pulse by the charging time of the capacitor 5. This property to form the output pulses with a delay relative to the acting pulse allows the proposed generator operating in the standby mode to be used as a shift cell multiphase shaper x. An example of such use is shown in FIG. 2 a device containing sequentially connected cascades of the same type, each of which uses the proposed generator, representing its modification, performing threshold element 4 on a thyristor with a zener diode in its control electrode circuit, limiter 7 on the zener diode and current source 11 in the form of a resistor 12 connected to a voltage source 2. The proposed device, having a number of pins according to the number of stages, in which the base of the key transistor of each subsequent stage is connected to a load element connected in series with the hoporoBbiM element, has the ability to independently adjust the time intervals between output pulses (Fig. Pros, b, c, d), formed by adjacent cascades, due to the possibility of independent control of the limiter level in each of the cascades. Thus, the proposed generator has wide functionality.

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Claims (1)

PULSE GENERATOR containing a serially connected first current source and a threshold element with negative resistance, a capacitor connected first to the common bus, distinguishing it by the fact that, in order to provide the possibility of controlling the amplitude of the output pulses, a voltage limiter, a diode, a second current source and a transistor, connected by a collector-emitter gap between the first current source and the second output of the capacitor, and the base to the second current source are introduced into it, while the diode is connected parallel to the collector-emitter transistor gap.